Electron microscopy
  
Cmc21 A21am (36) Space Group
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Table 1859. Cmc21 (A21am, 36) space group.

Name in the International Tables for Crystallography
 Cmc21
Lattice type
 C
Patterson space group
 65
Point group
 mm2
Crystal system
 Orthorhombic
Laue class
 mmm
Asymm
 0 ≤ x ≤ 1/2 and 0 ≤ y ≤ 1/2 and 0 ≤ z ≤ 1/2
Number of symmetry operators
 8
Symmetry (atomic coordinates)
X, Y, Z; -X, -Y, 1/2+Z; X, -Y, 1/2+Z; -X, Y, Z; 1/2+X, 1/2+Y, Z; 1/2-X, 1/2-Y, 1/2+Z; 1/2+X, 1/2-Y, 1/2+Z; 1/2-X, 1/2+Y, Z
Crystal examples
 Ferroelectrics: BaMnF4, BaFeF4, BaNiF4, BaZnF4, BaMgF4, BaCoF4 (Ba2+ ions are surrounded by the eight F- ions).
SrBi2Ta2O9 (Ferroelectric orthorhombic phase, a = 5.5196 Å, b = 5.5202 Å and c = 25.0521 Å): Sr(4a) at (0, 0.2589, 0), Bi on Sr site(4a) at (0, 0.2589, 0), Bi(8b) at (0.4721, 0.7759, 0.2007), Sr on Bi site(8b) at (0.4721, 0.7759, 0.2007), Ta(8b) at (0.5206, 0.7480, 0.4149), O1(4a) at (0.559, 0.280, 0), O2(8b) at (0.587, 0.682, 0.3346), O3(8b) at (0.739, 0.988, 0.2576), O4(8b) at (0.766, 0.976, 0.0715), O5(8b) at (0.769, 1.030, 0.5849)
SrBi2Nb2O9, Bi2.2Sr0.8Nb1.9Sc0.1O9
Bi2.25Ca0.5Na0.25Nb2O9: a = 5.4845 Å, b = 5.4549 Å, c = 24.9195 Å

 

 

 
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